/**
 *  将WGS-84(国际标准)转为GCJ-02(火星坐标):
 */
export function transformFromWGSToGCJ(latitude, longitude) {  
	var lat = "";
	var lon = "";
	var ee = 0.00669342162296594323;
	var a = 6378245.0;
	var pi = 3.14159265358979324;

	if (isLocationOutOfChina(latitude, longitude)) {
		lat = latitude;
		lon = longitude;
	} else {
		var adjustLat = transformLatWithXY(longitude - 105.0, latitude - 35.0);
		var adjustLon = transformLonWithXY(longitude - 105.0, latitude - 35.0);
		var radLat = latitude / 180.0 * pi;
		var magic = Math.sin(radLat);
		magic = 1 - ee * magic * magic;
		var sqrtMagic = Math.sqrt(magic);
		adjustLat = (adjustLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
		adjustLon = (adjustLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
		latitude = latitude + adjustLat;
		longitude = longitude + adjustLon;
	}
	return {
		latitude: latitude,
		longitude: longitude
	};
}

/**
 *  将GCJ-02(火星坐标)转为百度坐标:
 */
export function transformFromGCJToBaidu(latitude, longitude) {
	var pi = 3.14159265358979324 * 3000.0 / 180.0;

	var z = Math.sqrt(longitude * longitude + latitude * latitude) + 0.00002 * Math.sin(latitude * pi);
	var theta = Math.atan2(latitude, longitude) + 0.000003 * Math.cos(longitude * pi);
	var a_latitude = (z * Math.sin(theta) + 0.006);
	var a_longitude = (z * Math.cos(theta) + 0.0065);

	return {
		latitude: a_latitude,
		longitude: a_longitude
	};
}

/**
 *  将百度坐标转为GCJ-02(火星坐标):
 */
export function transformFromBaiduToGCJ(latitude, longitude) {
	var xPi = 3.14159265358979323846264338327950288 * 3000.0 / 180.0;

	var x = longitude - 0.0065;
	var y = latitude - 0.006;
	var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * xPi);
	var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * xPi);
	var a_latitude = z * Math.sin(theta);
	var a_longitude = z * Math.cos(theta);

	return {
		latitude: a_latitude,
		longitude: a_longitude
	};
}

/**
 *  将GCJ-02(火星坐标)转为WGS-84:
 */
export function transformFromGCJToWGS(latitude, longitude) {
	var threshold = 0.00001;
	// The boundary
	var minLat = latitude - 0.5;
	var maxLat = latitude + 0.5;
	var minLng = longitude - 0.5;
	var maxLng = longitude + 0.5;
	var delta = 1;
	var maxIteration = 30;
	while (true) {
		var leftBottom = transformFromWGSToGCJ(minLat, minLng);
		var rightBottom = transformFromWGSToGCJ(minLat, maxLng);
		var leftUp = transformFromWGSToGCJ(maxLat, minLng);
		var midPoint = transformFromWGSToGCJ((minLat + maxLat) / 2, (minLng + maxLng) / 2);
		delta = Math.abs(midPoint.latitude - latitude) + Math.abs(midPoint.longitude - longitude);
		if (maxIteration-- <= 0 || delta <= threshold) {
			return {
				latitude: (minLat + maxLat) / 2,
				longitude: (minLng + maxLng) / 2
			};
		}
		if (isContains({
				latitude: latitude,
				longitude: longitude
			}, leftBottom, midPoint)) {
			maxLat = (minLat + maxLat) / 2;
			maxLng = (minLng + maxLng) / 2;
		} else if (isContains({
				latitude: latitude,
				longitude: longitude
			}, rightBottom, midPoint)) {
			maxLat = (minLat + maxLat) / 2;
			minLng = (minLng + maxLng) / 2;
		} else if (isContains({
				latitude: latitude,
				longitude: longitude
			}, leftUp, midPoint)) {
			minLat = (minLat + maxLat) / 2;
			maxLng = (minLng + maxLng) / 2;
		} else {
			minLat = (minLat + maxLat) / 2;
			minLng = (minLng + maxLng) / 2;
		}
	}
}


/**
 *  判断经纬度是否超出中国境内
 */
function isLocationOutOfChina(latitude, longitude) {
	if (longitude < 72.004 || longitude > 137.8347 || latitude < 0.8293 || latitude > 55.8271)
		return true;
	return false;
}
function transformLatWithXY(x, y) {
	var pi = 3.14159265358979324;
	var lat = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
	lat += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
	lat += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
	lat += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
	return lat;
}
function transformLonWithXY(x, y) {
	var pi = 3.14159265358979324;
	var lon = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
	lon += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
	lon += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
	lon += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
	return lon;
}